Program.cs

using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.EntityFrameworkCore;
using Microsoft.IdentityModel.Tokens;
using Portfolio.Api.Configurations;
using Portfolio.Api.Data;
using Portfolio.Api.Handlers;
using Portfolio.Api.Services.Implementation;
using Portfolio.Api.Services.Interfaces;
using Serilog;
using System.Text;
using System.Threading.RateLimiting;

var builder = WebApplication.CreateBuilder(args);

// Logging Configuration 
Log.Logger = new LoggerConfiguration().ReadFrom.Configuration(builder.Configuration)
                                      .WriteTo.Console()
                                      .WriteTo.File("logs/portfolio-log.txt", fileSizeLimitBytes: 10 * 1024 * 1024, // 10MB
                                                                             rollOnFileSizeLimit: true,
                                                                             retainedFileCountLimit: 3)
                                      .CreateLogger();
builder.Host.UseSerilog();

// Database & Core Services
builder.Services.AddDbContext<AppDbContext>(options => options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

builder.Services.AddMemoryCache();
builder.Services.AddControllers();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

// Security Settings & DI
builder.Services.Configure<SmtpSettings>(builder.Configuration.GetSection("SmtpSettings"));
builder.Services.Configure<SecuritySettings>(builder.Configuration.GetSection("SecuritySettings"));

var securitySettings = builder.Configuration.GetSection("SecuritySettings").Get<SecuritySettings>();

// Rate limiting
builder.Services.AddRateLimiter(options =>
{
    options.AddPolicy("authPolicy", httpContext =>
        RateLimitPartition.GetFixedWindowLimiter(
            partitionKey: httpContext.Connection.RemoteIpAddress?.ToString() ?? "anonymous",
            factory: partition => new FixedWindowRateLimiterOptions
            {
                AutoReplenishment = true,
                PermitLimit = 5,
                Window = TimeSpan.FromMinutes(1),
                QueueLimit = 0
            }));
    // Policy for Contact/Feedback (3 requests per 10 minutes)
    options.AddPolicy("fixed", httpContext =>
        RateLimitPartition.GetFixedWindowLimiter(
            partitionKey: httpContext.Connection.RemoteIpAddress?.ToString() ?? "anonymous",
            factory: partition => new FixedWindowRateLimiterOptions
            {
                AutoReplenishment = true,
                PermitLimit = 3,
                Window = TimeSpan.FromMinutes(10),
                QueueLimit = 0
            }));
    options.RejectionStatusCode = StatusCodes.Status429TooManyRequests;
});
// Authentication
builder.Services.AddAuthentication(options => {
    options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
    options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
}).AddJwtBearer(options => {
    options.TokenValidationParameters = new TokenValidationParameters
    {
        ValidateIssuer = true,
        ValidateAudience = true,
        ValidateLifetime = true,
        ValidateIssuerSigningKey = true,
        ValidIssuer = securitySettings.Issuer,
        ValidAudience = securitySettings.Audience,
        IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(securitySettings.JwtKey)),
        ClockSkew = TimeSpan.Zero
    };
}); 
builder.Services.AddAuthorization();
// CORS Policy 
builder.Services.AddCors(options => {
    options.AddPolicy("DevPolicy", policy => {
        policy.WithOrigins("http://localhost:5173", "http://localhost:3000") // Vite & CRA ports
              .AllowAnyMethod()
              .AllowAnyHeader()
              .AllowCredentials(); // Required if sending cookies/auth headers
    });
});
builder.Services.AddScoped<IAuthService, AuthService>();
builder.Services.AddScoped<MailService>();
builder.Services.AddExceptionHandler<GlobalExceptionHandler>();
builder.Services.AddProblemDetails();

var app = builder.Build();

// Middleware Order Matters
app.UseExceptionHandler();
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}
app.UseHttpsRedirection();
app.UseRouting();
app.UseCors("DevPolicy");
app.UseRateLimiter();
app.UseAuthentication();
app.UseAuthorization();
app.MapControllers();

using (var scope = app.Services.CreateScope())
{
    var services = scope.ServiceProvider;
    var context = services.GetRequiredService<AppDbContext>();
    string adminEmail = securitySettings.RecieverEmail;
    await DbSeeder.SeedDataAsync(context, adminEmail);
}

try
{
    Log.Information("Cosmos Satellite (API) Online...");
    app.Run();
}
catch (Exception ex)
{
    Log.Fatal(ex, "Satellite Crash during startup.");
}
finally
{
    Log.CloseAndFlush();
}